1. Field of the Invention
The invention relates to a formulation for use as an adhesive component in the treatment of the hard substance of the tooth. In particular, the invention relates to an adhesive component which can be used for the treatment of enamel and dentine in connection with tooth restoration materials.
Tooth hard substance is built up from tooth enamel and dentine, which differ greatly in their composition. Tooth enamel is built up largely on a mineral basis, in particular from hydroxyapatite. Dentine, in contrast, consists to a considerable proportion, of organic units, such as collagen and other proteins, and contains more water. A specific serious problem in the field of conservative dentistry is to form a durable gap free bond of resin based curable dental filling materials normally used in dentistry, with the hard substance of the tooth (dentine and tooth enamel).
2. Description of Related Art
In the dental field, curable materials are used as dental filling materials. As curable materials, acrylic resin based filling materials, which can be cured by radical polymerization, are generally preferred. A disadvantage of these materials is in their shrinking during the curing process, thus contributing to the formation of gaps. Resin based dental fillings have the additional disadvantage that their adhesion to dentine is poor.
In order to improve bonding with the hard substance of the tooth, so called dental adhesives or bonding agents are used. In this context, dental adhesives are preferred which not only produce good adhesive values with respect to the dentine but also with respect to the enamel. Generally, it is expected that, to obtain an effective formulation, a plurality of components must be used. Thus, for example, in DE-A-38 28 170 and EP-B-0 361 033, a coating substance for collagen-containing materials is described, which consists of
a) aldehyde PA1 b) a water-soluble monomer with active hydrogen, PA1 c) a water-insoluble monomer with two or more polymerizable double bonds, PA1 d) a photo-initiator, PA1 e) water, PA1 f) a solubility agent and/or dispersant and PA1 g) known additives. PA1 a) (meth)acrylic acid esters containing formamide groups, PA1 b) (meth)acrylic esters which can form cross-linkings, PA1 c) solvents, PA1 d) optionally other additives, PA1 e) acids and, PA1 f) optionally a dispersant PA1 a) 20-75% by weight of glycerol di(meth)acrylate, PA1 b) 20-75% by weight of a volatile solvent miscible with water, PA1 c) 0.01-2.5% by weight of a photo-initiator and optionally PA1 d) 0-40% by weight of generally known additives and fillers. PA1 a) 20-70% by weight of glycerol di(meth)acrylate, PA1 b) 20-70% by weight of a volatile solvent miscible with water, PA1 c) 0.01-2.5% by weight of a photo-initiator, PA1 d1) 5-20% by weight of a filler and, optionally, PA1 d2) 0-25% by weight of generally known additives.
In U.S. Pat. No. 5,354,827 (and DE-A-41 05 550) dental adhesive formulation consisting of
is described. These are the type of dental adhesives over which the present invention provides an improved formulation.